Film deposition systems (e.g., chemical vapor deposition (CVD) systems and physical vapor deposition (PVD) systems) and plasma etching systems, which are used in the manufacturing processes of semiconductor devices such as integrated circuits (ICs) and large scale integration (LSI) circuits, each include a stage for accurately holding a substrate (e.g., silicon wafer) in a vacuum processing chamber. Japanese Laid-Open Patent Publication No. 2006-344613 describes an example of an electrostatic chuck, which is used as such a stage.
The electrostatic chuck includes an electrostatic chuck (ESC) attraction plate that electrostatically holds a substrate (silicon wafer). The electrostatic chuck performs temperature control to maintain the substrate held by the chuck at a controlled temperature. The electrostatic chuck may be a Coulomb electrostatic chuck or a Johnsen-Rahbek electrostatic chuck. The Coulomb electrostatic chuck generates attraction force that is highly responsive to the applied voltage. However, the Coulomb electrostatic chuck requires the application of high voltage. Further, the Coulomb electrostatic chuck cannot generate sufficient attraction force when the contact area is small between the ESC attraction plate and the substrate. The Johnsen-Rahbek electrostatic chuck generates sufficient attraction force even when the contact area between the ESC attraction plate and the substrate is small. However, the Johnsen-Rahbek electrostatic chuck requires current to be supplied to the substrate.
FIG. 7 is a cross-sectional view illustrating a referential example of an electrostatic chuck 80. The electrostatic chuck 80 includes a base 81 and an ESC attraction plate 83 bonded to the base 81 by an adhesive layer 82. The base 81 may be formed from, for example, aluminum. The adhesive layer 82 may be formed from, for example, silicone resin.
The base 81 supports the ESC attraction plate 83. The base 81 incorporates a heater 84. The heater 84, which generates heat when supplied with voltage, maintains the ESC attraction plate 83 at a controlled temperature with the adhesive layer 82.
The ESC attraction plate 83 incorporates an electrode 85. The electrode 85 is a thin-film electrostatic electrode. The electrode 85 is connected via a power supply unit 86 to a direct current (DC) power supply 87, which is arranged outside the electrostatic chuck 80.
FIG. 8 is a partially enlarged view of the power supply unit 86 illustrated in FIG. 7. The power supply unit 86 includes a power supply terminal 86A. A distal portion 86B of the power supply terminal 86A is electrically connected to the electrode 85 and is in contact with a lower surface of a wiring layer 85A, which is bonded to the adhesive layer 82. The electrode 85 is electrically connected to the DC power supply 87 (refer to FIG. 7) via the wiring layer 85A and the power supply terminal 86A. In the example of FIG. 8, an elastic member 86C, which is coupled to a basal portion of the power supply terminal 86A, presses the power supply terminal 86A against the lower surface of the wiring layer 85A.
The electrostatic chuck 80 includes a tubular insulator 88. The insulator 88 functions to insulate the power supply terminal 86A from the aluminum base 81. However, as indicated by the thick double-headed arrow in FIG. 8, the distal portion 86B of the power supply terminal 86A is insulated from the base 81 solely by the silicone resin adhesive layer 82. Any voids in the adhesive layer 82 or any insufficient formation of the adhesive layer 82 around the distal portion 86B of the power supply terminal 86A may result in insufficient electric insulation of the adhesive layer 82. This may cause discharge between the distal portion 86B and the base 81.